The venomous tentacula is a highly agressive and venomous plant. It has a toothsome plant mouth and tentacles, it sometimes spits poisonous spikey seeds. Students are permitted to swear if the plant tries to strangle them.
Professor Minerva McGonagall's late husband was killed by a venomous Tentacula bite.
When Harry goes to visit Professor Slughorn, he was busy harvesting Venomous Tentacula leaves.
Derwent Shimplin once ate an entire venomous Tentacula for a bet and survived, he's still purple though.